NMR techniques enable signals from metabolites in tissues, cells or granules to be monitored non-invasively. 31P NMR is used to measure levels of ATP, ADP, Pi, and intracellular pH. NMR studies of 13C enriched metabolites allow the elucidation of details of their metabolism. Spin echo 1H NMR enables the signals from many metabolites to be observed by removing the background of protein, membrane and water signals. These techniques are being developed and applied to several cancel cell lines grown in culture, and to several kinds of cellular secretary granules.